1. Field of the Invention
The present invention relates generally to an apparatus and a method for detecting the motion of an object from input images, and more particularly, to a method for determining the presence of a user's hand tremor or intentional motion during the recognition of an image through photographing.
2. Description of the Related Art
The most frequently used methods for detecting a motion from a moving picture include block matching and optical flow. The block matching method, which is performed by sampling, has a high speed, and the optical flow method, which is performed by optimization, has a relatively lower speed but demonstrates a more precise performance. An Unsymmetric-cross Multi-Hexagon-grid Search (UMHexagonS) method, which is one of the block matching methods and is experimentally known to show the highest performance, is frequently used for high-speed motion detection. For example, the UMHexagonS method is described in detail in Zhibo Chen, et al., “Fast integer-pel and fractional-pcl motion estimation for H.264/AVC”, Journal of Visual Communication & Image Representation (Online Available Oct. 19, 2005).
In the UMHexagonS method, a search area is sampled in each step. During sampling, a full range is first searched, and then the search range is narrowed to a local range. However, applications based on a mobile camera, which may include character recognition of an interest region, division of a region, and analysis of a region, require a motion existence determining method appropriate for the user environment. Accordingly, a precise motion detecting technique in an interest region is required that has a higher speed than a conventional technique. Also, in order to improve the calculation speed, a method for reducing a size of a block to be matched may be employed.
FIG. 1 is a diagram illustrating a difference in motion estimation according to a size of a block to be matched. In FIG. 1, to-be-matched blocks 10 and 20, before motion of an object, are indicated by dotted lines. To-be-matched blocks 12 and 22, after motion of the object, are indicated by solid lines. In recognizing characters on the surface, when larger-sized to-be-matched blocks 20 and 22 are used, there is a high possibility that the to-be-matched blocks 20 and 22 include edges on the surface. This increases the precision of motion detection, but decreases a detection speed. However, when smaller-sized to-be-matched blocks 10 and 12 are used, there is a high possibility that the to-be-matched blocks 10 and 12 do not include edges on the surface. This increases a motion detection speed but decreases a detection precision. Further, a hexagonal search method or a diamond search method has a low detection precision.